Known is an image processing system including an image processing apparatus and a server connected each other. The server is configured to authenticate each user of the image processing apparatus based on user information. The user information may include user identification information and restriction information. The user identification information is for identifying the particular user. The restriction information is for indicating how the performance of certain functions of the image processing apparatus is restricted. The image processing apparatus is configured to restrict performance of the image processing for each user in accordance with authentication result at the server. Examples of restriction on the image processing may be maximum printing amount in a day, color printing not permitted and facsimile transmission not permitted.